Hyde Park, London is 3.1 times larger than Riverside Park (Manhattan).
Area: 1 km2 calculated
Hyde Park is one of the largest parks in London, and one of the Royal Parks of London, famous for its Speakers' Corner. The park was the site of the Great Exhibition of 1851, for which the Crystal Palace was designed by Joseph Paxton. Wikipedia
Area: 0 km2 calculated
Riverside Park is a scenic waterfront public park on the Upper West Side of the borough of Manhattan in New York City, operated and maintained by the New York City Department of Parks and Recreation. Wikipedia